Field of the Invention
The present disclosure relates to an image forming apparatus using an electrophotographic system, such as a printer, a multifunction peripheral, a facsimile machine and the like.
Description of the Related Art
The image forming apparatus performs image forming processing by transferring a toner image formed on a photoreceptor to a recording medium such as a sheet. The toner remaining on the photoreceptor without being transferred after transferring the toner image (hereinafter referred to as “residual toner”) is removed by a cleaner. The removed residual toner is contained in a waste toner container which is attachably/detachably provided in the image forming apparatus as waste toner. The image forming apparatus which forms a color image comprises a plurality of photoreceptors and is configured to contain all the waste toner in one waste toner container. Thereby, the waste toner container is required to have a corresponding capacity. The waste toner container is replaced when the waste toner is fully loaded.
Japanese Patent Application Laid-open No. 2002-148884 discloses an image forming apparatus comprising a waste toner container with a plurality of receiving ports for receiving a waste toner. The waste toner recovered by cleaners respectively provided on a plurality of photoreceptors is separately recovered into the waste toner container from each receiving port. To detect that the waste toner is fully loaded, the waste toner container comprises a light transmission sensor. When the waste toner in the waste toner container is accumulated and light from the light transmission sensor is shielded, the output of the light transmission sensor changes. Thereby, the image forming apparatus detects that the waste toner is fully loaded in the waste toner container.
Japanese Patent Application Laid-open No. 5-188835 discloses a toner recovery device comprising two detection sensors to distinguish the waste toner amount in a waste toner container in two stages. When a first detection sensor detects waste toner, the toner recovery device notifies in advance that the waste toner will be fully loaded. When a second detection sensor detects the waste toner, the toner recovery device notifies that the waste toner is fully loaded. Then, the toner recovery device automatically stops the operation of an image forming apparatus. United States Patent Application Publication No. US2009/060536 discloses an image forming apparatus which detects a waste toner amount in a waste toner container, and notifies in advance that the waste toner container will be fully loaded. Then, based on a number of printed sheets through an image forming processing performed thereafter, the image forming apparatus assumes and notifies that the waste toner container is fully loaded.
Japanese Patent Application Publication Laid-open No. 2002-148884 only detects that the waste toner is fully loaded in the waste toner container and does not notify in advance that the waste toner container will be fully loaded. Also, the light transmission sensor sometimes wrongly detects that the waste toner is fully loaded in the waste toner container when the light transmission sensor is contaminated. Japanese Patent Application Laid-open No. 5-188835 and United States Patent Application Publication No. US2009/060536 notify in advance before the waste toner container is fully loaded and assumes a filling ratio of the waste toner in the waste toner container.
A screw is provided in the waste toner container. By conveying and uniformly leveling the waste toner using the screw, the waste toner container is configured to fill the toner as much as possible in the waste toner container. With the conventional waste toner container, a state of the waste toner in the waste toner container cannot be checked. The state of the waste toner changes depending on a use state of the image forming apparatus, environmental temperature, environment humidity, and the like. There may be a case where, due to the change of the state of the waste toner, a load is rapidly applied to the screw, which results in deteriorating conveyance efficiency of the waste toner and the filling ratio of the waste toner in the waste toner container differs from what is assumed. Thereby, it is important to appropriately prompt a user to replace the waste toner container depending on the state of the waste toner container.
Thereby, an image forming apparatus which predicts the state of the waste toner contained in the waste toner container and prompts the user to replace the waste toner container at appropriate timing is desired. Also, an image forming apparatus which suppresses wrong detection of notification with regard to the replacement of the waste toner container is desired.